Ok I have bad news for everyone. I've been to my dealer. The answer is :

IF you have a Xdrive M-sport(M-paket) in 18 (style 400M) with staggered(8x18 and 8.5x18) setup 225/45/18 and 255/40/18 summer setup. The ONLY way to put winter tyres and don't have DSC problems (and possibly not ruin bmw warranty on differencials) :

1) To put 225/45/18 and 255/40/18 winter tyres WITH RUNFLATS. I installed non runflats(pirelli sottozeros) in the same setup and DSC is failing. This is due to the fact winter tyres has softer structure and DSC will fail on non runflats.

2) To put squire setup (all tyres are the same) , but you will have to buy 2 additional front wheels to put on the rear 8x18 (as rears are 8.5x18).

So welcome to the world of bmw sales. I actually don't know is it worth to hunt for runflats or buy 2 more wheels , as the tyres size is quite rare and I can't fit other wheels (less than 18") because I have M performance brakes

Ok I have bad news for everyone. I've been to my dealer. The answer is :

IF you have a Xdrive M-sport(M-paket) in 18 (style 400M) with staggered(8x18 and 8.5x18) setup 225/45/18 and 255/40/18 summer setup. The ONLY way to put winter tyres and don't have DSC problems (and possibly not ruin bmw warranty on differencials) :

1) To put 225/45/18 and 255/40/18 winter tyres WITH RUNFLATS. I installed non runflats(pirelli sottozeros) in the same setup and DSC is failing. This is due to the fact winter tyres has softer structure and DSC will fail on non runflats.

2) To put squire setup (all tyres are the same) , but you will have to buy 2 additional front wheels to put on the rear 8x18 (as rears are 8.5x18).

So welcome to the world of bmw sales. I actually don't know is it worth to hunt for runflats or buy 2 more wheels , as the tyres size is quite rare and I can't fit other wheels (less than 18") because I have M performance brakes

Well that sure sucks. I'm still curious as to my situation. I will be getting the car with a 19" staggered setup. BUT my winters will be 18x8 square setup.

I think with FTM you won't have a DSC issue because the vehicle adapts to tire circumference. As where with TPMS your car will not, and you will get a DSC issue. I've never seen F30 with winters have this issue. I also mounted a set of 20" aftermarket non run flat winters on a car and it was fine.

Ok I have bad news for everyone. I've been to my dealer. The answer is :

IF you have a Xdrive M-sport(M-paket) in 18 (style 400M) with staggered(8x18 and 8.5x18) setup 225/45/18 and 255/40/18 summer setup. The ONLY way to put winter tyres and don't have DSC problems (and possibly not ruin bmw warranty on differencials) :

1) To put 225/45/18 and 255/40/18 winter tyres WITH RUNFLATS. I installed non runflats(pirelli sottozeros) in the same setup and DSC is failing. This is due to the fact winter tyres has softer structure and DSC will fail on non runflats.

2) To put squire setup (all tyres are the same) , but you will have to buy 2 additional front wheels to put on the rear 8x18 (as rears are 8.5x18).

So welcome to the world of bmw sales. I actually don't know is it worth to hunt for runflats or buy 2 more wheels , as the tyres size is quite rare and I can't fit other wheels (less than 18") because I have M performance brakes

Your dealership is trying to Bend you over and F you in the arse man.

Now, unsure about winters on a staggered setup (that's pointless), but I have NON run flat tires on 18x8's and with a high enough air inflation, I'm no longer DSC'ing all over the place.

I have purchased staggered rims/tires for summers only...you might have to just purchase some non-staggered's for the winters, but you aren't locked into run flats.

Ok I have bad news for everyone. I've been to my dealer. The answer is :

IF you have a Xdrive M-sport(M-paket) in 18 (style 400M) with staggered(8x18 and 8.5x18) setup 225/45/18 and 255/40/18 summer setup. The ONLY way to put winter tyres and don't have DSC problems (and possibly not ruin bmw warranty on differencials) :

1) To put 225/45/18 and 255/40/18 winter tyres WITH RUNFLATS. I installed non runflats(pirelli sottozeros) in the same setup and DSC is failing. This is due to the fact winter tyres has softer structure and DSC will fail on non runflats.

2) To put squire setup (all tyres are the same) , but you will have to buy 2 additional front wheels to put on the rear 8x18 (as rears are 8.5x18).

So welcome to the world of bmw sales. I actually don't know is it worth to hunt for runflats or buy 2 more wheels , as the tyres size is quite rare and I can't fit other wheels (less than 18") because I have M performance brakes

Very strange. Xdrive must be overly sensitive.

With AWD you have to make sure that the front and rear tires all have the same diameter.
Did you also make sure you were running the proper tire pressures front and rear?

If all of that is correct, I think BMW needs to answer as to why non RFT's, with the same diameter, and proper psi are causing the problem.
I'd like to read their explanation as to why RFT versions of the same tires will work.

I have direct connections in my BMW dealership , most knowledgable mechanic answered that the sidewalls are too soft. The modern F30 xdrive DSC feel the difference. And will cut out the power.

I've tried a lot of pressure configurations , nothing works.

I actually drive with DSC on till 65km/h , then I shut down the DSC or there are no way you could overcome the 80km/h barier , even on dry non snowy road.

And the actual feel of the drive is different A LOT between SUMMER RFT and WINTER non-RFT same diameter/high/wide. I've tried it on dry road and it's driving a toyota after bmw , expecially in the corners.

But BMW should warn the users about it.

It's now -14C , and 80cm of snow on most roads =] , if i didn't have xdrive I would sit home most of the time.

18 400m , staggered setup on non RFT pirellisottozerro

Quote:

Originally Posted by RPM90

Very strange. Xdrive must be overly sensitive.

With AWD you have to make sure that the front and rear tires all have the same diameter.
Did you also make sure you were running the proper tire pressures front and rear?

If all of that is correct, I think BMW needs to answer as to why non RFT's, with the same diameter, and proper psi are causing the problem.
I'd like to read their explanation as to why RFT versions of the same tires will work.

I have direct connections in my BMW dealership , most knowledgable mechanic answered that the sidewalls are too soft. The modern F30 xdrive DSC feel the difference. And will cut out the power.

I've tried a lot of pressure configurations , nothing works.

I actually drive with DSC on till 65km/h , then I shut down the DSC or there are no way you could overcome the 80km/h barier , even on dry non snowy road.

And the actual feel of the drive is different A LOT between SUMMER RFT and WINTER non-RFT same diameter/high/wide. I've tried it on dry road and it's driving a toyota after bmw , expecially in the corners.

But BMW should warn the users about it.

It's now -14C , and 80cm of snow on most roads =] , if i didn't have xdrive I would sit home most of the time.

18 400m , staggered setup on non RFT pirellisottozerro

Yes, winter/snow tires can actually suck when they are not being driven on snow and/or very cold temps.
It's a major reason why I don't use them. The conditions I drive in the majority of winter around here, like 90%, is cold with dry or damp road surfaces. Actual "winter/snow" conditions are not that often and get cleaned up pretty quickly leaving cold, wet or slushy surfaces. AS tires handle those conditions very well.

Of course there will be huge differences in handling and ride comparing summer performance tires to winter/snow tires. Most snow tires are not designed to provide performance driving on snow conditions.
The newer winter sport tires are designed to give some performance back, but they also give up some of their snow ability. They are between a true snow tire and a very good AS tire.
Maybe you should try some of that type of winter tire. Along with AWD it should make for a better combination.

If DSC is sensing slipping tires are highway speeds, even when you apply very little throttle, I'd be worried and I would not use those tires in those conditions. If the tires are slipping while simply moving forward, then they're braking performance in those conditions can be dangerous.
But, this is only true if DSC is working properly and is actually detecting tire slippage.

What exactly about the sidewall does that tech think is causing the DSC to activate?
Softer sidewalls causing DSC to activate? Makes no sense, especially if it's activating once you get to highway speed. At highway speeds there is quite a bit less torque being applied to the drive wheels. It's not likely that the tires are actually slipping or losing grip while going forward.
If anything, in warmer temps snow tires will have even more bite/grip on the road surface.
As for cornering, handling will be mushy as the sidewalls are soft but so is the tread, which is going to squirm under lateral load.